1. Field of the Invention
This invention pertains to high power LED devices for use in lighting products. More particularly, the invention relates to a high power LED lamp or multiple LED lamp design for use in lighting products and a source of heat removal therefrom.
2. Discussion of the Art
Current state of the art light emitting diode (LED) technology is less than 10 percent efficient in the visible spectra. The LED lamps of the GaN (gallium nitride) technology create white light by the conversion of blue or UV spectral emissions using phosphors and dyes to convert light into the white spectra.
The light output for a single LED is below that of known incandescent lamps, which are approximately 30 percent efficient in the visible spectra. Flashlights, using incandescent bulbs, have approximately 20 lumens of light output. An LED device having a comparable light output power density necessitates a larger LED design or a design comprising a multiple LED configuration. Further, a new source of heat removal is also required as the battery cannot be the sole heat removal source, since it will heat up and create hazardous conditions in the battery, such as thermal runaway, excessive heating of the battery chemicals, thus causing chemical leaking, bums, corrosion, and fire.
Moreover, an alternate form of direct energy absorbing cooling must be incorporated into the lamp housing, or inserted into the battery containment area, to handle the temperature rise in both the hand or other holding means as well as the LED device itself More particularly, the LED device becomes less efficient when heated to a temperature greater than 100xc2x0 C., thus creating a declining return in the visible spectra. The intrinsic phosphor conversion efficiency therefore drops dramatically as the temperature increases above an approximately 90xc2x0 C. threshold.
Thus, there is a particular need for an improved high power LED device for use in lighting products, such as flashlights and the like, which is capable of a light output of about 20 lumens and further includes an efficient source of heat removal therefrom.
A new and improved high power lamp structure having an efficient source of heat removal is provided. Briefly, in accordance with one embodiment of the present invention, an LED lamp structure is provided which has a plurality of LED die arranged in a multi-dimensional array, each of the LED die having a transparent substrate and a semiconductor material deposited on a surface of the substrate. Each of the LED die emits light from the top, bottom and sides of the die and is arranged on the multi-dimensional array so that the emitted light from each of the LED die does not contact another of the LED die. The LED lamp further includes a reflector for gathering and focusing of the emitted light from each of the LED die to approximate a high power LED lamp.
A principal advantage of the present invention is that a multi-LED lamp design is disclosed wherein several LED die are positioned so that the light emitted from each die does not conflict with light emitted from other LED die and is gathered and focused to approximate the 20 lumens output needed for a standard flashlight.
A second advantage of the present invention is that a LED lamp-like structure having a single, high power LED die as well as a source of heat removal therefrom can be used in a standard flashlight.
Still another advantage of the present invention is that an integrated phase change cooling concept, using a phase changing media for lighting products having LED devices, including flashlights, is disclosed, which enables the flashlight to be on for sustained periods of time, without a perceptible rise in temperature.
Still another advantage of the present invention is that an LED flashlight having light energy on a surface equivalent to that of a conventional filament incandescent bulb is disclosed.
Still another advantage of the present invention is that an LED lamp having enhanced thermal performance through the incorporation of electrically insulative, thermally conductive material is disclosed.
Still a further advantage of the present invention is that a flashlight is disclosed having longer lamp life, long battery life, and increased resistance to breakage of the bulb when the flashlight is dropped.
Still another advantage of the present invention is that a low cost assembly lighting product is disclosed for high volume appliance construction, particularly for flashlights of the hand-held variety.
Still another advantage of the present invention is that an LED equivalent to a conventional incandescent bulb, is disclosed for use in connection with the upgrade or retrofit of flashlight devices as a structural enhancement.
Still a further advantage of the present invention is that an enhanced lamp and lensing structure yielding good light flux area as compared to a conventional incandescent bulb flashlight is disclosed for use in the mass production of novel flashlight design.
Still a further advantage of the present invention is the use of integrated phase change cooling concepts, enabling an LED light source and phosphor structure, to be maintained at a constant fixed temperature for a sustained period of time, thus allowing the light source, and the hand held appliance, to maintain a constant light energy output level, due to the temperature maintenance characteristics of the phase change material(s).